What is PHP?
PHP is a server side scripting language. that is used to develop Static websites or Dynamic websites or Web applications. PHP stands for Hypertext Pre-processor, that earlier stood for Personal Home Pages.
PHP scripts can only be interpreted on a server that has PHP installed.
The client computers accessing the PHP scripts require a web browser only.
A PHP file contains PHP tags and ends with the extension “.php”.
PHP code may be embedded into HTML code, or it can be used in combination with various web template systems, web content management systems, and web frameworks. PHP code is usually processed by a PHP interpreter implemented as a module in the web server or as a Common Gateway Interface (CGI) executable. The web server combines the results of the interpreted and executed PHP code, which may be any type of data, including images, with the generated web page. PHP code may also be executed with a command-line interface (CLI) and can be used to implement standalone graphical applications.
What does PHP stand for?
PHP means – Personal Home Page, but it now stands for the recursive backronym PHP: Hypertext Preprocessor.
PHP code may be embedded into HTML code, or it can be used in combination with various web template systems, web content management system and web frameworks.
What Can PHP Do?
- PHP can generate dynamic page content
- PHP can create, open, read, write, delete, and close files on the server
- PHP can collect form data
- PHP can send and receive cookies
- PHP can add, delete, modify data in your database
- PHP can be used to control user-access
- PHP can encrypt data
Why PHP (1) ?
- PHP runs on various platforms (Windows, Linux, Unix, Mac OS X, etc.)
- PHP is compatible with almost all servers used today (Apache, IIS, etc.)
- PHP supports a wide range of databases
- PHP is free. Download it from the official PHP resource: www.php.net
- PHP is easy to learn and runs efficiently on the server side
Php Syntax
<!DOCTYPE html> <html> <head> <title>PHP Test</title> </head> <body> <?php echo '<p>Welcome</p>'; ?> </body> </html> |
A PHP file can also contain tags such as HTML and client side scripts such as JavaScript.
- HTML is an added advantage when learning PHP Language. You can even learn PHP without knowing HTML but it’s recommended you at least know the basics of HTML.
- Database management systems DBMS for database powered applications.
- For more advanced topics such as interactive applications and web services, you will need JavaScript and XML.
Why use PHP (2) ?
You have obviously head of a number of programming languages out there; you may be wondering why we would want to use PHP as our poison for the web programming. Below are some of the compelling reasons.
- PHP is open source and free.
- Short learning curve compared to other languages such as JSP, ASP etc.
- Large community document
- Most web hosting servers support PHP by default unlike other languages such as ASP that need IIS. This makes PHP a cost effective choice.
- PHP is regular updated to keep abreast with the latest technology trends.
- Other benefit that you get with PHP is that it’s a server side scripting language; this means you only need to install it on the server and client computers requesting for resources from the server do not need to have PHP installed; only a web browser would be enough.
- PHP has in built support for working hand in hand with MySQL; this doesn’t mean you can’t use PHP with other database management systems. You can still use PHP with
- Postgres
- Oracle
- MS SQL Server
- ODBC etc.
- PHP is cross platform; this means you can deploy your application on a number of different operating systems such as windows, Linux, Mac OS etc.
Functions
PHP defines a large array of functions in the core language and many are also available in various extensions; these functions are well documented in the online PHP documentation. However, the built-in library has a wide variety of naming conventions and associated inconsistencies, as described under history above.
Custom functions may be defined by the developer, e.g.:
function getAdder(int $x): \Closure { return function(int $y) use ($x) : int { return $x + $y; }; } $adder = getAdder(8); echo $adder(2); echo $adder(null); $adder = getAdder([]); |
PHP Objects
Basic object-oriented programming functionality was added in PHP 3 and improved in PHP 4. This allowed for PHP to gain further abstraction, making creative tasks easier for programmers using the language. Object handling was completely rewritten for PHP 5, expanding the feature set and enhancing performance. In previous versions of PHP, objects were handled like value types. The drawback of this method was that code had to make heavy use of PHP’s “reference” variables if it wanted to modify an object it was passed rather than creating a copy of it. In the new approach, objects are referenced by handle, and not by value.
PHP 5 introduced private and protected member variables and methods, along with abstract classes, final classes, abstract methods, and final methods. It also introduced a standard way of declaring constructors and destructor, similar to that of other object-oriented languages such as C++, and a standard exception handling model. Furthermore, PHP 5 added interfaces and allowed for multiple interfaces to be implemented. There are special interfaces that allow objects to interact with the run time system. Objects implementing Array Access can be used with array syntax and objects implementing Iterator or Iterator Aggregate can be used with the foreach language construct. There is no virtual table feature in the engine, so static variables are bound with a name instead of a reference at compile time.
class Person
{
public $firstName;
public $lastName;
public function __construct($firstName, $lastName = '') {
$this->firstName = $firstName;
$this->lastName = $lastName;
}
public function greet() {
return 'Hello, my name is ' . $this->firstName .
(($this->lastName != '') ? (' ' . $this->lastName) : '') . '.';
}
public static function staticGreet($firstName, $lastName) {
return 'Hello, my name is ' . $firstName . ' ' . $lastName . '.';
}
}
$he = new Person('John', 'Smith');
$she = new Person('Sally', 'Davis');
$other = new Person('iAmine');
echo $he->greet();
echo '<br />';
echo $she->greet();
echo '<br />';
echo $other->greet();
echo '<br />';
echo Person::staticGreet('Jane', 'Doe');
|